bzr diff -r 10..20 http://foo" unsupported

[Martin Pool]

bzr diff can't show the diff between a range of revisions against a remote repository. It tries to open it as a WorkingTree, which is not supported.

It probably shouldn't try to open a WorkingTree unless it's actually going to diff against the current working copy.

[Martin Pool (mbp)]

Robert says: there's already a helper function in builtins which will take care of opening either the branch or the directory, depending on whether there is a branch or not. (Or at least there should be such a thing, or it can be extracted from cmd_log?)

[Jules Bean (jules)]

It's not just http, either. The same problem affects you if you have a non-working tree repository accessed by any method. Since 'bzr push' creates non-working-tree repositories this is quite annoying.

Diff between two versions clearly shouldn't need a working tree to operate.

[Vincent Ladeuil (vila)]

Jules, I undo your change of the title otherwise just reading the title makes the bug looks strange.

[Ian Clatworthy (ian-clatworthy)]

There are a large number of Use Cases here I can imagine we want to support. We may not implement all of those immediately but I'd like to ensure we're agreed on an interface that is both easy-to-love and scalable. As I see it, we need the power to:

* compare pretty much any combination of working tree, branch revision, another working tree, anther branch revision
* optionally filter by a list of file and directory names.

Looking at SVN's diff command (http://svnbook.red-bean.com/nightly/en/svn.ref.svn.c.diff.html), it's usage is:

    svn diff [-r N[:M]] [TARGET[@REV]...]
    svn diff [-r N[:M]] --old OLD-TGT[@OLDREV] [--new NEW-TGT[@NEWREV]] [PATH...]
    svn diff OLD-URL[@OLDREV] NEW-URL[@NEWREV]

And here's the usage for git-diff (http://www.kernel.org/pub/software/scm/git/docs/git-diff.html):

    git-diff [<common diff options>] <commit>{0,2} [--] [<path>…]

I prefer the git approach of tree/branch URLs on the command line (as opposed to --old and --new + special cases) but suggest they go after the file list. Here's the proposed usage:

  bzr diff [FILE...] [FROM_LOCATION] [TO_LOCATION]

The full text of the proposed help including examples is attached.

[Martin Pool (mbp)]

I think I'd rather just take the git syntax, including the -- separator. Why?

You can usefully do a selected file diff without specifying both the paths. If we rely on them being the last two then you cannot do that.

Having just done a diff it might be nice to cursor up and add a filename to filter it. (Not a very strong argument.)

Is there any particular reason to put them at the start?